This invention relates to an aqueous granulation plant.
In aqueous granulation, the product for granulation (for example, molten slag, a molten alloy, copper matte) is placed in a powerful flow of water. This flow of water granulates, solidifies and cools the product. The granules are then removed from the granulation water.
Such aqueous granulation plants comprise a granulation tank fitted for injection of granulation water and also a device for removing the granules from the granulation water. A conventional granule removal device comprises a sedimentation tank, separate from the granulation tank, in which the granules settle.
The object of the present invention is the design of a simple granulation plant which facilitates granule removal. According to the invention this aim is attained by an aqueous granulation plant according to the present invention.
The aqueous granulation plant according to the invention comprises, in a recognised manner, a granulation tank fitted for injection of granulation water in order to granulate the molten product, a sedimentation tank separate from the granulation tank, in which the granulated product settles in granule form and a distributor to transfer the water/granule mixture from the granulation tank into the sedimentation tank. According to an important aspect of this invention, the sedimentation tank comprises a number of concentration tanks. It will be seen that when the water is fed into the sedimentation tank by the distributor, it is distributed among the various concentration tanks in which the granules settle according to their specific weight. Concentration of the granules in the concentration tanks according to their specific weight makes removal easier. Its modular design also enables the configuration of the sedimentation tank to be optimised for the product to be granulated.
In a preferred embodiment the sedimentation tank comprises a supporting structure and concentration tanks suspended from the supporting structure.
The concentration tanks are advantageously in the shape of a hopper with a horizontal top edge, allowing them to be suspended from the supporting structure. These edges are the only contact area between the supporting structure and the concentration tanks.
Two adjoining concentration tanks are advantageously arranged so that their top edges are adjacent. The water can then flow from one tank to the other over these adjacent top edges.
The sedimentation tank advantageously has a peripheral wall that rises above the top edges of the concentration tanks. This peripheral wall, however, comprises one or more overflow openings to allow the clarified granulation water to flow out of the sedimentation tank.
Partitions rising above the top edges can be erected between two concentration tanks. By means of such partitions, different paths can be defined for the water/granule mixture in the sedimentation tank. For example, a longer path can be arranged to favour settlement of fines.
The hopper-shaped concentration tanks advantageously discharge into a delivery pipe fitted with a sealing device. This enables either the material flow to be halted or the concentration tank to be emptied.
A water removal device may be fitted upstream of the sealing device. This water removal device comprises for example a filter sleeve separating a central duct from an annular water collecting chamber. The granulation water can thus be filtered by the filter sleeve and escape via the water collecting chamber, while the granules pass through the central duct after the sealing device opens.
In a first embodiment, the concentration tanks nearest to the distributor are connected to a draining drum. The granules that gather in these concentration tanks are discharged to the draining drum for separation of the granules from the granulation water.
The concentration tanks farthest from the distributor can then be connected to a hydrocyclone in order to extract the fines from the granulation water.
In a second embodiment, at least one conveyor is positioned underneath the concentration tanks to collect the said granules that gather in the said concentration tanks when the sealing devices are open, at least one said conveyor being for example fitted with a perforated belt to allow the granulation water to drain away.